The invention relates to network users which transmit data and energy via separate or over the same lines, whereby the data and the energy of each network user is maintained.
In such networks, data and energy from distant sensors, actuators, apparatus and computers are exchanged and supplied to network users via the network.
The network transmits the data via 4 to 20 mA-interfaces using an analog manner or transmits data digitally via the serial interfaces RS 232, V 24. In both cases, energy is frequently transmitted to the remote apparatus with additional lines. A user in the network will immediately reply to a request from a second user by transmitting data.
It is known, to transmit data and energy of sensors in areas protected against explosion according to NAMUR, via the same lines. In all cases, the data are only transmitted between two points. The network users which are for measuring, controlling and regulating use network drivers during transmission to supply energy into the network. In my German Offenlegungsschriften Nos. 33 33 847 and 33 13 240 and in my U.S. Pat. application Ser. No. 649,372 filed on Sept. 11, 1984, I have disclosed a local network operating according to the RSMA/CD method which needs to be coupled to the network only as an additional IC-unit. An example of such a network is set forth in my German Offenlegungsschriften No. 34 27 350 and in my U.S. Pat. application Ser. No. 758,389 filed on July 24, 1985 and now U.S. Pat. No. 4,760,571. In these networks, the network drivers supply the energy to the network, and they are less suitable for the transmission of data and energy, because they require a high degree of energy for transmission. Accordingly, a separate network controller and/or a processor is always required for data transmission.
Consequently, the coupling of users which are usually easily controllable becomes unnecessarily time consuming and costly. In addition, there are not any elements which permit the minimization of energy in the network or in the network users and the allocation of different energies throughout the network.